Browsing by Author "Jeys, Thomas H."

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Collisional ionization in RB (NS,ND) -SF [backward], collisions
    (1985) Lu, Fan; Dunning, F. Barry; Walters, G. King; Jeys, Thomas H.
    Tbe thereotical work of Matsnzawa based on the essentially free electron model suggests that the rate constant for collisional ionization of a high rydberg atom is essentially the same as that for attachment of free electron haying the same momentum distribution. In the present work we test the essentially free electron model by comparing rate constants measured for the following reaction with those expected on the basis of free electron studies. The data are in good agreement indicating that studies of Rydberg atom collisions can provide information on very-low-energy electron interaction.
  • Thumbnail Image
    Item
    Development of a computer controlled Fizeau wavemeter
    (1985) Gray, Damien Francis; Dunning, F. Barry; Jeys, Thomas H.; Mutchler, Gordon S.
    A Fizeau wavemeter bas been developed that has demonstrated an accuracy of 1 part in 1^6 across the visible spectrum and 5 parts in 1^7 across any 1 A interval. The present design is a modified version of that initially proposed by Gardner. The design was optimized by developing a computer model of the instrument. This model suggests that the theoretical accuracy limit for this type of wavemeter is on the order of 1 part in 1^8.
  • Thumbnail Image
    Item
    L-changing in Na(Ns, Np)-Xe collisions
    (1984) McIntire, John P.; Dunning, F. Barry; Jeys, Thomas H.; Duck, Ian M.
    A crossed atomic beam/pulsed laser technique and electric field ionization have been used to study Na(nS,nP)-Xe collisions for 28 =< n =< 52. The predominate mode for destruction of the parent nS,nP atoms is l-changing. The time evolution of the A-mixed population is monitored at several times after laser fire and fit to a rate equation to determine the rate constants for l-changing. The data can be qualitatively explained by appealing to the free electron model and applying simple energy transfer arguments to the Rydberg electron-target interaction. Present results are compared to other experimental data.
  • Thumbnail Image
    Item
    Penning ionization studies in a flowing helium afterglow
    (1985) Keiffer, Richard Sullivan; Dunning, F. Barry; Walters, G. King; Jeys, Thomas H.
    Penning Ionization reactions in a flowing helium afterglow are studied through measurements of the ejected electron energy distributions, P(e), and through spin angular momentum conservation measurements. Measurements of electron energy distributions from the Penning Ionization of Ar, N2O, CO2 by He(23S) metastable atoms compare quite well with known energy distributions. In addition, the Penning electron energy distribution of Rb is reported for the first time. Spin dependencies of the Penning process are studied by spin orienting the He(23S) metastable atoms prior to their collision with the reactant species. Measurements of the polarization of the electrons ejected in the Penning process provide a means of discerning the relative strengths of spin conserving and spin erasing entrance channels. The degree of spin conservation measured in the Penning Ionization of Cl2 and O2 (55% and 3%) agree qualitatively with predictions made from P(e) measurements of Cl2 and 2.
  • Thumbnail Image
    Item
    Self frequency-locking of a dye laser to the center of an atomic transition frequency
    (1985) Johnson, Lee K.; Jeys, Thomas H.; Walters, G. King; Baker, Stephen D.
    A new method of passive frequency stabilization is used to lock the laser output frequency to an atomic transition. A Michelson interferometer replaces the output coupler of a broadband standing wave dye laser. A sodium vapor absorber placed in one leg of the interferometer increases feedback only at the absorption frequency, forcing the laser to operate at this frequency. A fully Doppler-broadened vapor Results in simultaneous laser output at the 2S1/2-2P1/2 2S1/2-2P3/2 transition frequencies (dV=52 GHz) with linewidtns of 3 GHz each. An atomic beam of 1 MHz Doppler width produces simultaneous operation on both the [equation] transition frequencies (AV = 1.77 GHz) with linewidths of 1 MHz each. This technique should be applicable to other absorbers and may be of interest in optical pumping applications.
  • Thumbnail Image
    Item
    The calibration, response, and energy resolution of a segmented, sampling hadron calorimeter between 10 and 130 GEV/C
    (1983) Johns, Kenneth Arthur; Roberts, Jabus B.; Miettinen, Hannu E.; Jeys, Thomas H.
    A large acceptance sampling calorimeter with wavelength shifter readout for studying high p^ hadronic interactions has been assembled at Fermilab. The calorimeter consists of a 132 segment tower structure of S-8.5 radiation lengths of lead followed by 6-8 absorption lengths of iron. A procedure to balance the responses of all 528 calorimeter modules using muons steered by a computer controlled rotating dipole is described. Results on the resolution, linearity, and uniformity of the calorimeter obtained with electrons and hadrons in the momentum range 1-13 GeV/c are presented. For iron sampling thicknesses of 1.3cm, 1.9cm, and 2.8cm the hadron energy resolution is found to be .76, .82, .91/E respectively, while the electron energy resolution obtained is .27, .35, and .37/E.